Tropical Storm Henri forms

The tropics spawned another October surprise today, when Tropical Storm Henri formed in the face of adverse levels of wind shear. Henri is under about 20 - 25 knots of wind shear, which ordinarily prevents rapid development like we witnessed this afternoon. However, the environment is quite moist, and Henri is over warm waters, 29°C. An ASCAT pass from 11:37am EDT showed Henri had winds of 40 mph. Satellite loops show that Henri has managed to rapidly develop a large area of intense thunderstorms with cold cloud tops in just a few hours, though the high shear is keeping any thunderstorms from developing on the west side of the center. Water vapor satellite images show that there is some dry air to Henri's northwest, and this dry air will act to slow Henri's growth some. The dry air is creating strong downdrafts that are apparent on visible satellite images as arcs of cumulus clouds spreading out from where the downdraft hits the ocean surface, along the northwest side of Henri's center.

None of the reliable global computer models showed Henri would develop, and the models all favor weakening and dissipation of Henri by Thursday, due to high wind shear of 20 - 25 knots. The official NHC forecast goes along with this scenario, but think there is a medium (30 - 50% chance) that Henri will not dissipate. By Friday, wind shear in the vicinity of Henri (or its remains) is predicted to fall to the low to moderate range. Even if Henri has dissipated by that point, regeneration into a tropical storm may occur. The track of Henri after Friday is problematic, as the storm will be in an area of weak steering currents. Several of the models favor a track to the west-southwest into the Caribbean, across Hispaniola. Residents of the Dominican Republic and Haiti should anticipate that Henri or its remains may bring flooding rains to Hispaniola by Saturday. It is also possible that Henri will get pulled northwards and recurved out to sea, and not affect the Caribbean at all, though.

Figure 1. Latest satellite image of Henri.

A little tropical weather for EnglandThe remnant circulation of Tropical Storm Grace is currently making landfall in Southwest England. Grace's remains brought sustained winds of tropical storm force--41 mph--to one buoy off the coast last hour, and 38 mph to the Sevenstones Lightship buoy. you can track the progress of Grace via our wundermap for the region.

Figure 2. The remnant circulation of Tropical Storm Grace scoots by to the south of Ireland in this visible satellite image taken at 1pm EDT 10/06/09. Image credit: UK Met Office.

644.Oh, that's easy, that would be the color of your aura.I've made a promise to myself never to be mean-spirited on this blog; it's a learning and information tool -- so I'm out now, nothing I need to "win" here. Have a nice day, seriously.

Good Morning. Having trouble interpreting the current CIMSS shear chart. Looks like Henri is slipping west of the noted band of 30-40 knots and the next noted band of 20 knots is to it's W/NW at around 20N/60W with Henri in the middle right now between the two. Anyone have a guess at what the sheer over Henri is right now (during the course of today) or do I just assume anywhere between 20-30 knots for the time being?

if you look at post 612 the BAM models just switched South again.......heck 10minutes ago they stayed over water into the Bahamas! Models are going to bounce around a bit more with this as it nearly stalls.

CARIBBEAN AND TROPICAL N ATLC...TROPICAL STORM HENRI AT 18.4N 55.3W AT 0300 UTC WITH WINDS OF 40 KT WITHIN GUSTS TO 50 KT IS FORECAST TO WEAKEN TO A MINIMAL TROPICAL STORM NEAR 18.4N 55.3W WED MORNING AND WEAKEN FURTHER TO A 30 KT DEPRESSION BY 20.5N59/7W WED NIGHT BEFORE DIMINISHING TO A REMNANT LOW NEAR 21.8N 61.9W THU MORNING AS A HIGHLY AMPLIFIED NORTHERN STREAM TROUGH SWEEPS THROUGH THE CENTRAL N ATLC. WINDS AND SEAS ASSOCIATED WITH HENRI SHOULD DIMINISH BELOW 20 KT/8 FT CRITERIA OVER THE TROPICAL N ATLC ZONE AROUND MID-DAY THU.

Quoting antonio28:Henri is moving Westward as a pointed out by me and other blogger yesterday night. Advisories should be issue at 11am for the nothermost Leeward island it is not going north anytime soon, NHC compleatly miss this one. Remember when the post it the red alert "Henri will pass Far north of the noethen island" when I read that only one exprecion came to my mind was LOL! They are smoking good stuff.

that would be me. And, yes, since it is embedded within the low-level flow (because pressures with Henri are still relatively high), it will continue to move west.

Also, for those who say don't follow the convection, the shear for Henri is supposed to be out of the sw to ne, however convection is building to the sw. This means two possible things:

1) Shear may be beginning to lessen2) Henri is trying to move south of due west.

Henri is moving Westward as a pointed out by me and other blogger yesterday night. Advisories should be issue at 11am for the nothermost Leeward island it is not going north anytime soon, NHC compleatly miss this one. Remember when the post it the red alert "Henri will pass Far north of the noethen island" when I read that only one exprecion came to my mind was LOL! They are smoking good stuff.